The Highly Strung View

The Art of Science has long held a fascination so I had to share the BBC's remarks on String Theory after being lead to the site by Richard Brunner on facebook.  This entry is a reminder that our private universe is small indeed when compared with the larger realities.

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Currently there are two 'golden rules' of physics - General Relativity, which governs the large-scale Universe and quantum mechanics, which governs the nanoworld of atoms. The problem is that the two laws don't really agree with each other. What is needed to bridge the gap is an extra clause that links the two, a 'theory of everything', known as quantum gravity, that has yet to be discovered.

Superstring theory is a contender for this prize. The idea is that the zoo of thousands of tiny 'elementary' particles that exist are not disparate entities but all originate from the same source - a vibrating string. The easiest way to imagine this is to think of a guitar string. Pressing on the fretboard alters the length of the vibrating string, producing a new note. Similarly, in superstring theory, elementary particles can be thought of as different notes played on the same string. Each string is unimaginably small, about 10²⁰ (100 billion billion) times smaller than a proton. Vibrating the string at different frequencies generates all the different types of oddly-named elementary particles, such as 'gluons', 'weakons' and 'strange quarks'.

But in order to vibrate, strings need lots of room. In fact they need more room than is available in the four-dimensional world in which we live (made up of height, width, depth and time). Superstring theory requires the presence of ten dimensions! But where have the other six gone? Physicists have suggested that during the Big Bang these other dimensions were folded away, or 'compactified' leaving only four to expand and evolve.

But what does this mean for dark matter, the missing mass of the Universe? If superstring theory is right then it could provide an unusual answer to this cosmic mystery. Although these hidden dimensions remain too small to be measured, gravity can travel in between them. Hence the extra mass that is missing from our Universe may just be fallout from these unseen dimensions.

First we'll have to wait to see whether superstring theory is accepted as the crucial 'theory of everything'. If it is, then astronomers might have finally discovered where dark matter has been hiding out.